Assessment of pulmonary function in older children and adults is routinely accomplished through the measurement of maximal expiratory flow-volume curves (MEFVCs) and fractional lung volumes (FLVs). Because these tests require the voluntary performance of specific respiratory maneuvers, it has not been possible to obtain comparable measurements in infants and toddlers. In 1993 at Columbus Children's Hospital (CCH), a method was developed and an apparatus constructed which enabled the measurement of standard adult-type pulmonary function tests including MEFVCs and FLVs in sedated infants and toddlers. Substantial evidence now exists documenting the physiologic and clinical equivalency of these measurements made in infants and toddlers to those made in order children and adults. The purpose of this project is to construct, technically evaluate, and test in children a commercial prototype apparatus which permits the measurement of standard adult-type pulmonary function tests in sedated infants and toddlers. Feasibility will be established by comparing measurements obtained using the prototype with measurements made using currently existing equipment at CCH. This Phase I work will provide a fully evaluated working commercial prototype device ready for manufacture and distribution to 10 pediatric tertiary care centers where it will be used in phase II as a measure of outcome in a multi-center therapeutic trial for infants with cystic fibrosis. Commercial availability of this technology will allow clinicians to more accurately diagnose and more effectively manage infants and young children with respiratory disorders including cystic fibrosis, asthma, bronchiolitis, and bronchopulmonary dysplasia. The ability to perform adult-type pulmonary function tests in infants and toddlers should contribute substantially to the effort to prevent, treat, investigate, and cure the respiratory disorders of early childhood.